These investigators will study the effect of IGF-1 on patients with osteoarthritis of the knee of sufficient severity to require a knee joint replacement. Patients will undergo a knee arthroscopy and cartilage biopsies, and then will be randomized to receive either IGF-1 or placebo by intra-articular injections. After the injections end, the patient will have joint replacement. The GCRC will be utilized for the injections by the PI and phlebotomy by the nursing staff.